1. Field of the Invention
The present invention relates to a spatial light communication device which is used by being connected to a handheld terminal such as a handheld information terminal and a mobile phone and which transmits an information signal from a transmitter to a receiver, with the information signal superimposed on spatial light, for the purpose of providing a user with necessary information such as content information.
2. Description of Related Art
JP H11-24619 A has proposed a conventional audio guide system which uses, for example, infrared data communication to provide visitors at public facilities and the like with an audio guide such as information on facilities, description of exhibits on display and guidance of the facilities.
The conventional audio guide system is equipped with a recorder portion which records an audio signal, an FM transmitting circuit in which the audio signal reproduced from the recorder portion is subjected to frequency modulation (FM) and an infrared emitting portion which superimposes a transmitting signal output from the FM transmitting circuit on an infrared ray to emit the infrared ray. The audio guide system is installed at various areas such as a variety of exhibition sites in facilities.
Further, each audio guide system is provided with an infrared ray sensor for detecting humans and constituted so that visitors at facilities are given an infrared ray FM receiver to receive an audio guide. The audio guide system is used in such a manner that when a visitor having the infrared ray FM receiver comes close to the audio guide system, the infrared ray sensor detects the visitor and the audio guide system superimposes the audio guide on an infrared ray to transmit it to the FM receiver, by which the visitor listens to the audio guide through the FM receiver.
However, where the above-described conventional audio guide system is installed, for example, at a plurality of places in various types of facilities such as a gymnasium, a municipal hall, a museum and an art gallery, the audio guide is different depending on each place in various types of facilities. It is, therefore, necessary to prepare a record portion which records audio guide data thereof and allow an audio guide system at each installation place to store the data. Further, construction work is also necessary for installing these individual audio guide systems at various installation places. Thus, additional time and labor are necessary in the construction work for installation, which poses a problem.
Further, for example, in the case of a museum or an art gallery, an audio guide system is installed for each exhibit on display. And, the audio guide system requires a change of the audio guide every time exhibits on display are changed. However, as with the above case, it is necessary to store the thus changed audio guide data in each audio guide system. For this type of work additional time and labor are required and this poses a problem.
On the other hand, in recent years, handheld terminals such as mobile phones have been used quite extensively and are becoming essential items for most people in everyday life. In mobile phones, information such as phone calls, e-mail and images is usually transmitted via a mobile phone communication network by radio waves. And, therefore, transmission of the information is slow.
For this reason, for example, where people with visual disabilities moving around town or the like want to immediately obtain necessary precautionary information for a place of movement or where users moving around town or the like want to immediately obtain position information and map information of the place, they are not able to obtain the information in a timely manner by operating the mobile phones via a mobile phone communication network, or physically handicapped people are not able to immediately obtain necessary information.
Further, mobile phone communication networks by radio waves are mostly unusable at the time of a disaster such as an earthquake, and even in such a situation that a power source is available and users are able to use mobile phones at the time of a disaster, such as an earthquake, no necessary information is obtained through handheld terminals due to troubles of mobile phone communication networks by radio waves. This also poses a problem.